双排气膜孔冷却热弹耦合特性的分析

Study on Thermo-Elastic Coupling Characteristics of Dual-Row Film Cooling

关键词:  气膜冷却  平板  热应力  热弹耦合

Key words:  Film-cooling  Flat-plate  Thermal stress  Thermo-elastic coupling

摘要:

利用多场耦合的计算方法，研究了带双排冷却孔的平板气膜冷却热弹耦合特性，系统分析了吹风比、排列方式、流向间距对温度场和热应力场分布的影响规律。研究结果表明，平板内部作用力的方向与孔排展向一致，热应力集中于气膜孔的前缘和尾缘。低温区的位置与吹风比的大小有关，同时低温区的位置也决定了热应力极值的位置。对于顺排布置而言，上、下游射流的相互干扰和冷气流量的分配不均是导致其冷却效果稍差的主要因素。当吹风比小于1.0时叉排布置的冷却效果总体较优，气膜孔内热应力明显较小；但当吹风比增大至1.5时，叉排布置相对于顺排布置的优势明显缩小。增大流向间距有利于均衡上、下游气膜孔的流量，也有利于降低平板的温度梯度和气膜孔内的热应力。

Abstract:

Multi-field coupling calculating method was used to investigate the thermo-elastic characteristics of the flat-plate film-cooling with dual row of holes. The influences on the temperature filed and thermal stress field by blowing ratio，holes’ arrangement，streamwise distance were systematically studied. The results show that the direction of inner force of flat-plate is same as the lateral direction of the cooling holes，and the thermal stress concentrates on the leading edge and trailing edge of the cooling holes. The low-temperature zone，which can determine the location of the extreme value of the thermal stress，relates to the blowing ratio. The jet disturbance and mass flow inequality between the upstream and downstream can lead to the disadvantage of the aligned arrangement. The staggered arrangement，whose cooling performance is generally better than that of the aligned arrangement，has the relative low inner-hole thermal stress while the blowing ratio is less than 1.0. However，the advantage of the staggered arrangement over the aligned arrangement may obviously reduce while the blowing ratio increased to 1.5. The increase of the streamwise distance is helpful to balance the mass flow of the upstream and downstream cooling holes，and is also helpful to decrease the temperature gradient in the flatplate and the thermal stress in the cooling holes.